WhatsApp Web calls work Web-to-Web and Mobile-to-Mobile, but fail Web-to-Mobile
Title: WhatsApp Web calls work Web-to-Web and Mobile-to-Mobile, but fail between Web and Mobile
I’m trying to diagnose a WhatsApp calling issue and wanted to see if anyone else has seen the same pattern.
## Environment
- macOS
- WhatsApp Web running in Chrome / Electron-based WebView
- Proxy/VPN/TUN tested with multiple nodes
- UDP/STUN appears to work
- `RTCPeerConnection` exists in the browser
- Public IP changes correctly when proxy is enabled
## What works
I tested several combinations:
| Call direction | Result |
|---|---|
| WhatsApp Web ↔ WhatsApp Web | Works |
| Mobile WhatsApp ↔ Mobile WhatsApp | Works |
| WhatsApp Web ↔ Mobile WhatsApp | Fails |
This happens even when Web-to-Web calls are using different proxy nodes, and Mobile-to-Mobile calls also work across different nodes.
## What fails
When calling between WhatsApp Web and a mobile WhatsApp client:
- The call rings.
- The other side can answer.
- After answering, the call stays stuck on “Connecting”.
- Eventually WhatsApp shows a network-related warning, such as asking to check or switch the network.
- Media never connects.
## Things I already checked
- WebRTC exists:
```js
typeof RTCPeerConnection
// "function"